Funny sounds on MP3's

September 21, 2005 1:30 PM

Anyone else ever notice funny sounds on MP3's with particularily low-pitched male vocals?

Some MP3's by such low-level singers as Johnny Cash, Nick Cave and Leonard Cohen have a slight vocal effect where it sounds like they have a frog in their throats, has anyone else noticed this, I can hear it with all media playing programs and on all stereos.

posted by Cosine to media & arts (8 comments total)

Hmm, I don't really know what sound you're talking about (I don't have a low-male-voice song on both .mp3 and .cda to compare), but I'm guessing it's what audiophiles call a "compression artifact" (sounds that were not present in the original recording). MP3 is a lossy compression scheme, which means that it removes frequencies "scientifically proven" to be mostly unnecessary for the human listening experience; the "unnecessary frequencies" are often very necessary, and can cause problems if the .mp3s are created at a low bit-rate.
posted by muddgirl at 1:47 PM on September 21, 2005

Do you have any specific examples of songs where this happens?
posted by zsazsa at 1:49 PM on September 21, 2005

If you had an example it'd be fantastic, but I haven't had this happen when using better encoders and decent quality settings. mp3s encoded in 1996 on the other hand, all sound llike crap.
posted by I Love Tacos at 2:09 PM on September 21, 2005

examples - basically any track by the artists I have mentioned, or all of 'The Magnetic Fields' '69 Love Songs'.
posted by Cosine at 2:28 PM on September 21, 2005

cosine, what is the bitrate of the MP3s you are talking about? I archive stuff at 256K, variable rate using iTunes and don't hear any artifacts at those settings on a wide range of music.

I'll agree with muddgirl that what you are hearing is a compression artifact and will go away if you re-encode from CD at a higher rate.
posted by omnidrew at 2:47 PM on September 21, 2005

Yes, I have found this, and I'm no 'audiophile'.

Johnny Cash's 'The Man Comes Around' sounds like shit encoded with LAME set to it's highest quality settings -- 320kbs CBR.

Until iTunes was released for windows (I have a mac now), I had it ripped on my computer in .wav format, because the MP3 rip sounded awful.

It sounds much better at 128kbs AAC, but still noticably different from the original, and perfect encoded at higher bitrate AAC.

It's just a problem with the MP3 codec's psychoacoustic models -- It saves space by removing what it thinks you can't hear, and in this case it gets it all wrong.

The MP3 codec is pretty damn old, having been finalized around 1992. It's pretty rusty. It has real problems with real, imperfect voices like Johnny Cash -- it fails most at things that are somewhat random, like applause.
posted by blasdelf at 9:17 PM on September 21, 2005

Another way you get artifacts is MP3s that have been through more than one compression cycle. Say someone burned an audio CD from an MP3, then it doesn't matter how high you set your encoding when ripping, because you're starting out losing.
posted by dhartung at 10:31 PM on September 21, 2005

Thanks blasdelf, I'll check into ripping them to AAC and comparing.
posted by Cosine at 11:54 PM on September 21, 2005